Synthesis of Rhodizonic Acid and Croconic Acid

Event Center A & B

Compounds that are piezoelectric produce an electric charge in response to applied mechanical stress. As such, they can be used to measure changes in pressure, acceleration, strain, and force. Piezoelectrics are often used in ultrasound devices, sonars, light deflectors and modulators. Ferroelectric compounds are a subset of piezoelectric compounds. Ferroelectrics possess a spontaneous electric polarization that can be reversed when an external electric field is applied. Croconic acid, a five carbon cyclic oxocarbon acid, has recently been confirmed to be ferroelectric (Horiuchi, et al, Nature, 2010, 463, 789-792). It is hypothesized that other cyclic oxocarbon acids, such as the 6-membered ring rhodizonic acid, and the 3-membered ring deltic acid, may also be ferroelectric. It is also postulated that derivatives of these oxocarbon acids, might display similar piezoelectric or ferroelectric behavior. The purpose of this research is to synthesize croconic acid and rhodizonic acid, to grow single crystals of these substances, and to explore their piezoelectric/ferroelectric behavior. Croconic and Rhodizonic acid are synthesized through multi-step reactions. A precursor to both of these acids is the disodium salt of tetrahydroxy-pbenzoquinone, that can be prepared by the self-condensation of glyoxal under oxidative alkaline conditions. Once prepared, this disodium salt can then be oxidized and decarboxylated to form croconic acid, or oxidized in air to yield rhodizonic acid. Croconic acid has been synthesized with an average percent yield of 7%, while rhodizonic acid has been synthesized with an average percent yield of 12%.